Issue with posing after resizing
Apply Object Transformations When Rigging

The problem with the figure's foot is that the scale of the figure and the scale of the rig are not both equal. This can cause unusual behavior like what you experienced.  

To prevent this from happening, whenever you are joining a rig to a mesh, you must first always apply their scales so the scales are both set to 1.  

The reason for this is simple: when you import a figure, it will default to have a scale of 1. Also, when you add a rig, it too will default to a scale of 1. 

However, almost always the figure and the rig will be different sizes, so you naturally will change the scale and maybe even the rotation of one or the other so they match up and the rig fits right inside the model.

This results in a difference of scale (and maybe rotation) of the rig and the model. In your file, the figure's scale is 1, but your metarig's scale has been reduced down to 0.195:



(You can see the scale of objects in the Properties panel, which can be opened with N)

This difference of scales becomes problematic when the rig is joined to the figure. 

Therefore, whenever you finish scaling and/or rotating both your figure and your rig, you need to Apply Object Transformations to both the figure and the rig. When you are Applying Transformations, you can apply the location, rotation, and/or scale. 

Here is how you do that, first for either the rig or the figure, then for the other:


In Object mode, select either the rig or the figure
Then use one of these methods to apply transformations:  


3D View Header -> Object -> Apply -> Rotation &amp; Scale 
CTRLA -> Apply Rotation &amp; Scale





The main goal is to have the Rotation for both rig &amp; figure set to 0 for X, Y &amp; Z, and also to have the Scale for both be set to 1 on X, Y &amp; Z. 

Then your rig will work properly.